I agree with paul. Remove the upper shock mount and compress the shock, swing the shock outwards. The inner bolt can now be easily removed with a12 point 10mm socket.
Installing: bolt new shock to lower mount; align upper shock stud with mounting hole, then clip the safety wire and let the shock extend into the wheel well mounting hole!
It took me about 10 minutes to do each one last month, once the car was 'jacked' up and set to go.